Compensating lags in head-coupled displays using head position prediction and image deflection

Images on head-coupled systems are delayed by latencies in measuring head position and generating computer graphics. The objectives of this study were 1) to investigate the effects of time delays on head tracking performance; 2) to evaluate the use of an image deflection technique to reduce deleterious effects of delayed images; and 3) to investigate the application of a head position prediction algorithm to enhance the benefits of image deflection. There were significant decreases in head tracking performance when lags of 40 ms or more were added to a system with an inherent 40 ms lag. Lag compensation by image deflection significantly improved tracking performance with lags up to 380 ms. However, by deflecting the delayed image back to its prelag angular position, part of the picture was displaced beyond the edge of the screen. The amount of deflection required was reduced by a simple means of predicting the position of the head before applying deflection. Improved means of predicting head position would further reduce the required image deflection.